keep primary_key_identifier type

Author: Pantea Marius-ciclistu

src/Http/Middleware/Decorators/AbstractDecoratorMiddleware.php

@@ -203,10 +203,12 @@ protected function getListNewContent(Request $request, array $content, array $co
         foreach (($content['data'] ?? []) as $row) {
             $decoratedRow = $this->decorator->decorate((array)$row);
             $decoratedRow[AbstractResourceDecorator::PKI] ??= AbstractResourceDecorator::applyHtmlSpecialChars(
-                \implode($this->resourceModel::COMPOSITE_PK_SEPARATOR, \array_map(
-                    fn(string $pk): string => $row[$pk] ?? '',
-                    $pks ??= $this->getPks()
-                ))
+                ($onePk ??= \count($pks ??= $this->getPks()) === 1) ?
+                    $row[$firstPk ??= \reset($pks)] :
+                    \implode(
+                        ($this->relatedModel ?? $this->resourceModel)::COMPOSITE_PK_SEPARATOR,
+                        \array_map(fn(string $pk): mixed => $row[$pk] ?? '', $pks)
+                    )
             );
             $newContent['data'][] = $decoratedRow;
         }